Air cushion joint



April 6, 1937.

A. H. SCHAFFERT AIR CUSHION JOINT 'Filed oct. 22, 1954 Patented Apr. 6, 1937 UNITED STATES PATENT OFFICE AIR CUSHION JOINT Application October 2.2, 1934, Serial No. 749,4 41

l Olaim.

The present invention relates to expansion joints such as are widely used in the building of concrete roads to allow for the expansion and contraction of the material of the road. More particularly it relates to the type known as air cushion joints in which the sections of concrete are separated by a body of air which is covered by a sealing strip, usually of asphalt material.

Previously used joints of the air cushion type have been composed of pluralities of separate straight sections, which sections were placed in the road in end to end relation, each section being positioned at an angle to the adjacent ones. This method resulted in joints having top surfaces made up of a plurality of chords, and as concrete roads are transversely curved in a uniform crown, the tops of the joints and the road surfaces were not parallel curves to the distance between them, and consequently the spaces between sections to be lled with sealing material, varied. In order to conform with the variations, the filling has sometimes been done with melted material.

It has been found that a pre-formed strip of asphaltum has certain material advantages over a poured filler, but when a preformed filler is used with the type of joint above described, it is necessary to trim the top of such strip to make it conform to the crowned surface of the road.

The object of the present invention is to provide a joint and particularly an air cushion Joint which is longitudinally curved to conform to the crown of a road.

In the accompanying drawing:

Figure 1 is an elevation showing the joint in position in a roadway which is shown in section.

Figure 2 is a perspective view partly in section showing the joint inserted in a road.

Figure 3 is an enlarged elevation of a portion of the lower V-shaped member of the joint.

Figure 4 is a sectional view taken on the lines 4 4 of Figure 3. v

Figure 5 is a sectional view taken on the lines -5-5 of Figure3.

Figure 6 is as sectional plan view taken on lines 6-6 of Figure 3.

Figure 7 is a sectional plan view taken on lines 'I-l of Figure 4. A

The air cushion joint is composed of an upper or cap member 8 and a lower or base member 9.

The upper or cap member is preferably formed of material which will resist corrosion since it is important that it last for a. comparatively long period of time. Copper alloys have been found suitable. Advantageously it comprises a top wall (Cl. Sli-48) l0 and downwardly extending side walls il, terminating in outwardly extending flanges l2 which are shaped and rebent to engage portions of the base section. The top wall I0 may be formed with a central longitudinally extending channel l.

The lower member 9 may be formed of ferrous and relatively light material since it is unimportant that it resist corrosion after the concrete of the road has set. This member ,may be channelshaped, comprising a bottom wall lll and side walls l5, which terminate at their tops in outwardly extending flanges I6 shaped to interlock with the rebent flanges I2 of the cap member, as shownv in Figure 2.

In order to longitudinally curve the lower member 9, the material of the side walls is deformed at intervals in a manner which longitudinally contracts the lower portion of the member.

This is done by forming longitudinally spaced, outwardly extending corrugations Il of special form in the lower portion of the side walls l5 and the bottom' it. These corrugations begin at a pointbelow and spaced from the flanges i6 and comprise outer `walls I8 and side walls I9 which at the point of the beginning are at a very slight angle to the walls l5,.but which increase their angularity to such walls to substantially right angles as they'approach the bottom of the member 9. Thus the corrugations are greatest in outward extent from the walls l5 at their lowermost points, from where they taper inwardly until they merge with the said walls. Due to this formation of the corrugations, an increasing amount of the material of the walls I5 from top to bottom is bent from the plane of the walls, and there is a consequent shortening of the lower portion of the member, with an attendant longitudinal bending thereof.

Advantageously a. complete air cushion joint is composed of two similar sections 20, 2| joined together as by welding of their meeting ends.

In order to seal the joint to prevent moisture :and dirt from entering the pocket formed therein. a preformed sealing strip 22 is placed in the space between the sections of the concrete over the top of the cap strip 8. The strip 22 is formed with a projection 23 which lies in the channel I3 and the sides thereof are shaped to conform with the edges 24of the concrete sections.

An air cushion joint of this type has many advantages. It is of the same contour as the surface of the road which allows a. preformed sealing strip to be used without trimming. It is simple to manufacture, and inasmuch as it is in 55 one piece when positioned in the road, it is easy` to install. It is less expensive to install than a Joint made up of a plurality of straight sections. Finally it forms an eiiicient and durable air cushion joint.

From the foregoing, it is thought that the construction, operation and many advantages of @the herein described invention will be apparent to those skilled in the art without further description, and it will be understood that various changes in the size, shape, proportion and minor details of construction may be resorted to without departing from the spirit or sacricing any of the advantages of the invention.

bedded.

ADOLF H. SCHAFFERT. 

